1. Field of the Invention
The present invention relates to a home network system capable of transmitting digital video data and the like through a radio transmission channel, particularly to a technique for readily integrating a server apparatus and client apparatuses, which are connected to a network, into a group and setting the security thereof.
2. Description of Related Art
Recently, DVD/HDD recorders and personal computers, which are provided with personal video recorder (PVR) functions, have remarkably prevailed. Accompanying this, video resources which allow individuals viewing and listening thereto at home, has also continually been growing. Such contents as video information which are accumulated in a DVD/HDD recorder or personal computer, are required for users to enjoy anytime and anywhere. A technique which is capable of outputting the contents on a client apparatus such as a liquid crystal TV or the like, by using a home network, has been proposed. As a technique for transmitting a large amount of data such as video data and sound data at a high speed and in real time, for example, IEEE 1394 is adopted as a connecting interface for digital TV, digital video recorder or the like.
In these days, to readily connect devices, the DVD/HDD recorder, personal computer, liquid crystal monitor and the like are configured to be connected to one another by using a wireless LAN. As a typical technique of the wireless LAN, IEEE 802.11 using a 2.4 GHz waveband, which was standardized by the IEEE, has widely prevailed. The 2.4 GHz waveband is called as industrial, scientific and medical (ISM) band, which is a frequency band used for the purposes of industry, medical field, microwave oven or the like. In Japan, a waveband of 2.400 to 2.497 GHz is allotted for the wireless LAN.
However, in the home network system, when a communication is carried out by utilizing a radio transmission channel, for example, there is a problem of security such that devices within the home network may be accessed and controlled through an external communication device. Therefore, it is important to carry out an authentication operation before establishing the connection among the devices within the home network. As an authentication operation, the following methods are available. That is, authentication IDs of the respective devices which are connected with each other, are exchanged, and only when the respective authentication IDs match with each other, the communication can be started.
For example, JP 2003-309882A (Patent document 1) discloses a home network system in which a home server and a home electric appliance (white goods, e.g., a refrigerator, an air conditioner, an electric washing machine, an electric rice cooker, a microwave and the like) are connected to each other through electric cables. In order to control the electric appliance within the home network with one remote control unit, the home server is configured so that once a user sets up an authentication ID of the remote control unit to the home server, the home server automatically transmits the authentication ID of the remote controller, which has been set up therein, to the respective electric appliances. Accordingly, the authentication ID of the remote control unit does not have to be set up to each of the electric appliances, thus the user is relieved of such load.
As another example of the home network system, JP 2003-9265A (Patent document 2) discloses the following remote control system. That is, only a terminal at the remote control side or only the side to be remote controlled can be replaced, and a plurality of devices which are manufactured by different makers, are remote-controllable from an identical terminal.
In the technique disclosed in Patent document 1, a server apparatus (home server) and a client apparatus (electric appliance) are connected into a group through a wire. In comparison with to the case of communication through a radio transmission channel, the security between the server apparatus and the client apparatus is ensured at a high level, and by carrying out the authentication among the server apparatus, the client apparatus and the remote control unit, the security can be increased.
On the contrary, in the case where the communication is carried out through a radio transmission channel between the server apparatus and the client apparatus, the authentication is required even between the server apparatus and the client apparatus. If the authentication is not carried out between the server apparatus and the client apparatus, data may be erroneously transmitted to an external radio communication device, or conversely, electric appliances within the home network may be controlled through an external radio communication device; thus the security thereof is reduced accordingly. For example, when a system is configured so that a server apparatus and a client apparatus which are located adjacent to each other, automatically recognize each other, there is such a possibility that the system might recognize a similar system used by another person being partitioned by a wall.